Just as we were predicting the end of SIM technological development, along comes a technology which really could be a killer application - a complete GPS system embedded inside one.
At the SIMposium in Berlin, Blue Sky Positioning announced it has developed a complete GPS system, including the antenna, which physically fits …

Phone chassis as ariel

".....but when we take away the battery, take the SIM out of the phone, the signal is no longer there."

What I think he's trying to say is the SIM is inductively coupled to the phone's metal chassis (via an air-gap), and thus is using the chassis as an ariel. If the SIM is connected to the phone with a bit of ribbon cable, or a case-less dev-board phone is used, then the SIM won't work correctly, as it hasn't metal plate near it to use as an ariel.

No metal chassis

The last mobile phone with a metal chassis was dropped from high altitude to destroy a gun emplacement during the second Gulf war.

Modern phones simply do not usually have a metal chassis, the absence of which contributes to their light weight.

If you remove the battery from your phone you will typically discover that it has four electrical connectors, not the two that one would expect. The extra two are used for battery management.

From this we can conclude that mobile phone batteries contain WIRES, which if one is terribly smart and does not upset the circuitry, can be used as an antenna. This is similar to the technique for using headphone connecting leads as an aerial in small radios.